Electronic circuit designers have traditionally been concerned about controlling the heat that builds up during circuit operation. Heat control is vital to prevent individual component failure as well as a consequent circuit failure caused by failed components. The preferred method to control component and circuit heat is to dissipate excess heat into the atmosphere before the temperatures rise to a level where damage can occur. Heat dissipation is usually accomplished by associating heat transfer devices, such as heat sinks, with the components to absorb the component heat and radiate excess heat into the surrounding atmosphere.
The problems associated with heat control have become more pronounced as low profile and compact electronic systems have become the preferred choice of customers. These low profile and compact systems typically have design parameters that make it difficult to find space for all the required electronic components on the substrate of a printed wiring or circuit board, much less the heat transfer devices such components require to prevent heat related damage. For example, the specifications for a certain electronic system may call for a printed wiring or circuit board of no more than 125 square inches with a component height that cannot exceed 1.24 inches. Within this limited space, approximately 1700 electronic components must be accommodated, as well as the associated heat transfer devices necessary to remove over 100 watts of heat generated by the components.
Compact electronic systems also present additional manufacturing challenges. Limited component space means that specialized tooling may be required to assemble the heat transfer devices and their related components to the substrate. If specialized tooling is required, such tooling may have to be specially fabricated with a corresponding increase in the total production cost. In addition to specialized tooling, the manufacturing process often requires that the components be put together off the regular assembly line as sub-assemblies. When subassemblies are manufactured off line, additional handling problems must be addressed. Frequently, device leads have been inadvertently bumped or bent out of position between the time the assembly was built and when it is to be inserted in the substrate. When this happens, the operator must manually keep adjusting the device leads without the aid of the fixtures and jigs. Other problems include slowing the line down to accommodate such interruptions and the logistics of keeping track of parts, assemblies and subassemblies during the manufacturing process.
A number of the problems discussed above occur because heat transfer devices and mounts for such devices are not generally available on the commercial market for use in low profile and compact electronic assemblies. In fact, very few of the commercially available heat transfer devices are suitable for heat control when a large number of electronic components are required to be located in a restricted space. Most of the commercially available heat transfer devices are designed to accommodate only one or two electronic components, which means that several such devices are required to control the heat generated by a single circuit. Several heat transfer devices may be used in electronic systems where space is not a factor, but such is not acceptable in compact or low profile systems where space is at a premium.
In many cases where space is at a premium, the electronic components are mounted on heat spreaders and the spreaders are mounted on the substrate or printed wiring board with threaded studs and nuts. These spreaders frequently must be custom made when low profile or compact systems are manufactured. Such spreaders are frequently associated or combined with commercially available heat sinks to complete a heat control system. The use of spreaders on printed wiring or circuit boards typically means more and smaller parts are required. This is because the devices are usually fastened to the spreader with clamps, screws and nuts. Then the spreader assembly must be attached to both the substrate, as well as to other heat diffusing devices, which generally slows down the manufacturing process. Other heat diffusing devices are required because the spreaders, by themselves, do not have enough surface area to be effective as a stand-alone heat dissipating devices. Spreaders generally must be combined with a customized heat plate to increase the surface area.
Accordingly, what is needed in the art is a device and method that can be used to mount heat transfer devices and the associated electronic components on a substrate. The device should advantageously handle both spreaders and other heat transfer devices and provide for a completed electrical connection between the electronic components and the underlying circuit. Specifically, such a device should lend itself to being used in the manufacture of compact and low profile electronic systems.